A sensor of this type is already known from WO 87/05569, HEINTZ, KONIG & PACHNER/BOSCH, publ. 24 Sep. 1987, where an optical method based on diffraction and reflection is used for detecting the acceleration and the inclination of a motor vehicle. In this method, a beam of light emanating from an emitter is diffracted or reflected at the surface separating a liquid and a gas bubble that falls on a receiver if the gas bubble contained in the housing is in its initial position. However if, because of acceleration or inclination of the motor vehicle, the gas bubble is deflected from its initial position, the light beam is diffracted or reflected in a different direction at the surface separating a liquid and the gas bubble, and no longer falls on the receiver, so that a signal is triggered by the optical device.
This sensor has the disadvantage that the means required for realizing the optical method (emitter, receiver, etc.) entail a relatively high expenditure of mechanical, optical and electric parts.